Here's an idea I had years ago and tried to promote to some of the earliest wireless companies, such as Metricom, without success. I just posted it on Dave Farber's IP list, so I should write it up again for my own blog...
The idea is a win-win situation for wireless service and municipalities. Combine wireless data service with traffic light control. Offer a wireless mesh company the use of a city's traffic light poles -- which provide a nice high spot at every major intersection in town, with power available -- in exchange for using that network for traffic control. Indeed, I think this space is so valuable to the wireless companies that they should probably buy traffic control software and offer it free to the cities.
The bandwidth for light control is of course trivial. One could also support traffic cams (though hopefully not universal surveillance cams) to help provide dynamic adjustments to the traffic system.
Today, full-bore automatic traffic lights are expensive -- $150,000 in many cases. That's because of the need to bring in safety-equipment grade power, and to dig up the road to lay down vehicle sensors,
as well as data of course. That's changing. New lights use LEDs and thus a fair bit less power. (Some cities have realized that the LED switch pays for itself very quickly.) I think car sensor tech is changing too, and especially with a large market, either LIDAR or CCD cameras with automatic recognition should be capable of good traffic detection without digging up the road.
So it's a win all around. Cities get better traffic flow (and less gas is burned) and wireless networks sprout everywhere to compete with the monopoly cable/ILEC crew.
For places where a full street light is too expensive, I have also suggested the [wireless brokered 4-way stop](/archives/000118.html) as an alternative.